package leetcode;

public class leetcode101_对称二叉树 {
    public boolean isSymmetric(TreeNode root) {
        if(root==null){
            return true;
        }
        return dfs(root.left,root.right);



    }

    public  boolean dfs(TreeNode left, TreeNode right) {
        if (left==null&&right==null){
            return  true;
        }
        if(left==null||right==null){
            return  false;
        }
        if (left.val!=right.val){
            return  false;
        }
        return dfs(left.left,right.right)&&dfs(left.right,right.left);


    }
}
